On Thursday, a CIA Inspector General's report disclosed that that's exactly what happened. CIA employees hacked into a Senate computer, hunting for documents someone at the CIA thought the Senate should not have. It's unclear how high this went. Brennan has publicly apologized and formed an "accountability board" to determine who should get the blame and what the punishment should be.

There are two important considerations here.

One is Brennan himself, who holds one of the most important jobs in the Obama administration and is by most accounts a capable CIA director. Either Brennan knew what was going on and didn't tell the truth, or he didn't know what was happening in his own agency and looks dangerously uninformed. It's hard to say which is worse.

His credibility seems badly damaged, but the White House publicly defended him Thursday. Asked whether Brennan has believability problems, spokesman Josh Earnest said, "Not at all." What an odd thing to say about someone who either lied or was clueless.

Intelligence Committee member Mark Udall, D-Colo., said he has "lost confidence" in Brennan and called for his resignation. If more senators follow, Brennan would become a serious liability for President Obama.

The other issue is much more important than whether Brennan stays or goes.

The CIA appears to have directly violated the separation of powers doctrine that has worked for more than 200 years to keep the nation from becoming the sort of rogue state where secret police or the military can control the government. Given its history of domestic-spying scandals, the CIA should know better than to do anything that smacks of executive branch snooping on the legislative branch.

Brennan was given the director's job in part to try to get the spy agency past its controversial role during the war on terror, when the agency tortured suspected terrorists in contravention of law and longstanding American practice. The extent of what the agency did was hidden not just from the public but also from the members of Congress whose job it was to oversee it.

A Senate Intelligence Committee report, to be released soon, is expected to detail how the agency hid what it was doing, and how little useful information those practices produced.

If one of Brennan's assignments was to repair relations with Congress and rebuild the CIA's credibility, he has picked a strange way to go about it.

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